Background and Data Sources

In 2020 and 2021, the Census Bureau released several data products meant to demonstrate the effect of the Bureau’s new Disclosure Avoidance System (DAS) on population counts (using 2010 census data). The final demonstration product using the same privacy parameters applied to the 2020 census data was released in September 2023 for sex by age. The University of Minnesota’s IPUMS National Historical Geographic Information System (NHGIS) volunteered to convert the Census Bureau’s un-tabulated demonstration data into useful summary formats, linked to the published 2010 summary data. The intent of both organizations was for census data users to use these tabulated files to assess the impact of the DAS on their own local data. NHGIS tabulated data is located here. Information on the DAS is located here.

Note: Chicago is excluded due to being OOJ.



Total Municipality Population

The mean absolute change in population between the published 2010 data and the demonstration product data is -0.56 people. The largest absolute change in population between the demonstration data and the actual 2010 data is for Hoffman Estates with an increase of 18 people in the demonstration data. The mean percent change in population for all Cook County towns is 0.007%. There are 0 towns with a percent change in total population of more than 5%. The town with the largest absolute percent change in the demonstration total population counts is Bedford Park with a percent change of 0.52%. These patterns are reflected in the box plots below.


Conclusions: Total municipality populations are unlikely to be largely impacted by the 2020 DAS parameters and can be used without reservation.





Total Male Population for Municipality, regardless of Age

The mean absolute change in the total male population by municipality between the published 2010 data and the demonstration product data is 5.29 people. The largest absolute change in population is for Chicago Heights, with an increase of 23 people in the demonstration data. The mean percent change in the total male population for all Cook County munis is -0.02%. There are no towns with a percent change in the total male population of more than 5%. The town with the largest percent change in the demonstration Hispanic/Latino population counts is McCook with a percent change of -1.85%. The median percent change is 0% and the interquartile range is [-1.04%, 0.82%].


Conclusions: When aggregated, the variation introduced by the DAS settings for the total male population at the municipal level is negligible. There are no concerns for directionality. This means we can be reasonably confident in the 2020 jurisdiction-level total male population estimate, as calculated by the subtraction method.





Total Female Population for Municipality, regardless of Age

The mean absolute change in the total female population by municipality between the published 2010 data and the demonstration product data is 6.68 people. The largest absolute change in population is for Chicago Heights, with a decrease of 33 people in the demonstration data. The mean percent change in the total female population for all Cook County munis is -0.03%. There are no towns with a percent change in the total female population of more than 5%. The town with the largest percent change in the demonstration female population counts is McCook with a percent change of 2.5%. The median percent change is 0% and the interquartile range is [-0.07%, 0.05%].


Conclusions: When aggregated, the variation introduced by the DAS settings for the total female population at the municipal level is negligible. There are no concerns for directionality. This means we can be reasonably confident in the 2020 jurisdiction-level total female population estimate, as calculated by the subtraction method.





Males under 5 years of age by Municipality

The mean absolute change in the male population under 5 years of age by municipality between the published 2010 data and the demonstration product data is 4.17 people. The largest absolute change in population is for Elgin, with an increase of 23 people in the demonstration data. The mean percent change in the male population under 5 years for all Cook County munis is 0.15%. There are 6 towns with a percent change in the male population under 5 years of more than 5%. The town with the largest absolute percent change in the demonstration population counts is Forest View with a percent change of 33.33%. The median percent change is 0% and the interquartile range is [-0.77%, 0.79%].


Conclusions: When aggregated, the variation introduced by the DAS settings for the male population under 5 years of age at the municipal level largely balances out. There are no concerns for directionality. This means we can be reasonably confident in the 2020 jurisdiction-level male population under 5 years estimate, as calculated by the subtraction method. However, at the individual municipality level, 4% of municipalities have percent changes in population outside acceptable bounds. As expected, outliers are more common in areas where either the total population is smaller or the young male population is low. While this is notable and something to be wary about, it is not an overarching issue for a majority of municipalities.




Towns with >5% Change in Male Population Under 5 Years
Municipality Published Total Published Demonstration Percent Change
McCook 228 7 6 -14.29
Olympia Fields 4988 80 72 -10.00
Rosemont 4202 178 189 6.18
Bedford Park 580 16 17 6.25
Riverwoods 3660 78 87 11.54
Forest View 698 15 20 33.33


Males 50-54 Years by Municipality

The mean absolute change in the male population 50-54 years of age by municipality between the published 2010 data and the demonstration product data is 4 people. The largest absolute change in population is for Elgin, with a decrease of 16 people in the demonstration data. The mean percent change in the male population 50-54 years for all Cook County munis is -0.02%. There are 4 towns with a percent change in the male population 50-54 years of more than 5%. The town with the largest absolute percent change in the demonstration population counts is Forest View with a percent change of -10%. The median percent change is 0% and the interquartile range is [-0.64%, 0.68%].


Conclusions: When aggregated, the variation introduced by the DAS settings for the male population 50-54 years of age at the municipal level largely balances out. There are no concerns for directionality. This means we can be reasonably confident in the 2020 jurisdiction-level male population 50-54 years estimate, as calculated by the subtraction method. However, at the individual municipality level, 3% of municipalities have percent changes in population outside acceptable bounds. As expected, outliers are more common in areas where either the total population is smaller or the middle-aged male population is low. While this is notable and something to be wary about, it is not an overarching issue for a majority of municipalities.




Towns with >5% Change in Male Population 50-54 Years
Municipality Published Total Published Demonstration Percent Change
Forest View 698 30 27 -10.00
McCook 228 17 16 -5.88
South Chicago Heights 4139 136 129 -5.15
Bedford Park 580 24 26 8.33


Males 85+ Years by Municipality

The mean absolute change in the male population 85 years and older by municipality between the published 2010 data and the demonstration product data is 4 people. The largest absolute change in population is for Hanover Park, with an increase of 20 people in the demonstration data. The mean percent change in the male population 85 years and older for all Cook County munis is 4.26%. There are 55 towns with a percent change in the male population 85 years and older of more than 5%. The town with the largest absolute percent change in the demonstration population counts is East Hazel Crest with a percent change of 233.33%. The median percent change is 0.21% and the interquartile range is [-2.95%, 4.27%].


Conclusions: When aggregated, the variation introduced by the DAS settings for the male population 85 years and older at the municipal level is quite unstable. There are no concerns for directionality. However, this means we cannot be very confident in the 2020 jurisdiction-level male population 85 years and older estimate, as calculated by the subtraction method. At the individual municipality level, 40% of municipalities have percent changes in population outside acceptable bounds. As expected, outliers are more common in areas where either the total population is smaller or the older male population is low, which is not uncommon. Calculation of rates for the 85+ male population at the municipal level should be advised against for some municipalities. When rates must be calculated, strong data caveats should be included. Alternatively, a minimum population threshold of 500 or 1000 could be applied, below which rates would be censored.




Towns with >5% Change in Male Population 85 years and older
Municipality Published Total Published Demonstration Percent Change
Bedford Park 580 5 3 -40.00
Golf 500 8 5 -37.50
Rosemont 4202 20 13 -35.00
Willow Springs 5524 24 16 -33.33
Merrionette Park 1900 14 11 -21.43
Deer Park 3200 10 8 -20.00
Riverside 8875 53 43 -18.87
Phoenix 1964 17 14 -17.65
Northfield 5420 58 50 -13.79
Berkeley 5209 40 35 -12.50


Females under 5 years of age by Municipality

The mean absolute change in the female population under 5 years of age by municipality between the published 2010 data and the demonstration product data is 4.51 people. The largest absolute change in population is for Evanston, with a decrease of 21 people in the demonstration data. The mean percent change in the female population under 5 years for all Cook County munis is -0.03%. There are 10 towns with a percent change in the female population under 5 years of more than 5%. The town with the largest absolute percent change in the demonstration population counts is Forest View with a percent change of 19.05%. The median percent change is -0.07% and the interquartile range is [-0.96%, 0.65%].


Conclusions: When aggregated, the variation introduced by the DAS settings for the female population under 5 years of age at the municipal level largely balances out. There are no concerns for directionality. This means we can be reasonably confident in the 2020 jurisdiction-level female population under 5 years estimate, as calculated by the subtraction method. However, at the individual municipality level, 7% of municipalities have percent changes in population outside acceptable bounds. As expected, outliers are more common in areas where either the total population is smaller or the young female population is low. While this is notable and something to be wary about, it is not an overarching issue for a majority of municipalities.




Towns with >5% Change in Female Population Under 5 Years
Municipality Published Total Published Demonstration Percent Change
Riverwoods 3660 82 73 -10.98
Countryside 5895 117 106 -9.40
Bedford Park 580 17 16 -5.88
Thornton 2338 72 68 -5.56
North Riverside 6672 165 156 -5.45
Inverness 7399 113 119 5.31
Olympia Fields 4988 91 97 6.59
McCook 228 7 8 14.29
Barrington Hills 4209 62 71 14.52
Forest View 698 21 25 19.05


Females 50-54 Years by Municipality

The mean absolute change in the female population 50-54 years of age by municipality between the published 2010 data and the demonstration product data is 3.81 people. The largest absolute change in population is for Evanston, with an increase of 18 people in the demonstration data. The mean percent change in the female population 50-54 years for all Cook County munis is 0.55%. There are 5 towns with a percent change in the female population 50-54 years of more than 5%. The town with the largest absolute percent change in the demonstration population counts is McCook with a percent change of 66.67%. The median percent change is 0% and the interquartile range is [-0.45%, 0.51%].


Conclusions: When aggregated, the variation introduced by the DAS settings for the female population 50-54 years of age at the municipal level largely balances out. There are no concerns for directionality. This means we can be reasonably confident in the 2020 jurisdiction-level female population 50-54 years estimate, as calculated by the subtraction method. However, at the individual municipality level, 4% of municipalities have percent changes in population outside acceptable bounds. As expected, outliers are more common in areas where either the total population is smaller or the middle-aged female population is low. While this is notable and something to be wary about, it is not an overarching issue for a majority of municipalities.




Towns with >5% Change in Female Population 50-54 Years
Municipality Published Total Published Demonstration Percent Change
Forest View 698 31 24 -22.58
Dixmoor 3644 119 112 -5.88
Hodgkins 1897 50 55 10.00
Bedford Park 580 24 28 16.67
McCook 228 3 5 66.67


Females 85+ Years by Municipality

The mean absolute change in the female population 85 years and older by municipality between the published 2010 data and the demonstration product data is 5 people. The largest absolute change in population is for both Mount Prospect and Tinley Park, both with a decrease of 17 people in the demonstration data. The mean percent change in the female population 85 years and older for all Cook County munis is 2.06%. There are 34 towns with a percent change in the female population 85 years and older of more than 5%. The town with the largest absolute percent change in the demonstration population counts is Golf with a percent change of 50%. The median percent change is 0.34% and the interquartile range is [-1.56%, 4.27%].


Conclusions: When aggregated, the variation introduced by the DAS settings for the female population 85 years and older at the municipal level is quite unstable. There are no concerns for directionality. At the individual municipality level, 25% of municipalities have percent changes in population outside acceptable bounds. This is better for the male population at the same age, and so we can cautiously use the 2020 jurisdiction-level female population 85 years and older estimate, as calculated by the subtraction method. As expected, outliers are more common in areas where either the total population is smaller or the older female population is low, which is not uncommon. Calculation of rates for the 85+ female population at the municipal level should be advised against for some municipalities. When rates must be calculated, strong data caveats should be included. Alternatively, a minimum population threshold of 500 or 1000 could be applied, below which rates would be censored.




Towns with >5% Change in Female Population 85 years and older
Municipality Published Total Published Demonstration Percent Change
Thornton 2338 30 23 -23.33
Bedford Park 580 5 4 -20.00
Hodgkins 1897 21 17 -19.05
Richton Park 13646 85 71 -16.47
Riverdale 13549 76 72 -5.26
Country Club Hills 16541 174 165 -5.17
Flossmoor 9464 96 101 5.21
Hanover Park 37973 95 100 5.26
Worth 10789 103 109 5.83
Chicago Ridge 14305 205 217 5.85